GtkPaned::set_gutter_size
void set_gutter_size(int size);
set_gutter_size() can currently
be used to set the width or height in pixels of the gutter where the
dividing handle is based, only where the 1.2.* series of GTK+ is being
used to compile PHP-GTK. It does nothing in the win32 version.
Please note that this function is more than deprecated in GTK2; the
gutter_size property does not
exist in later releases. Do not use this function.